Apparatus and methods for replacing the knife units of a woodcutting machine



4 SheetsSheet 1 Filed June 11, 1965 I L- l March 21, 1967 Filed June 11, 1965 F. A. KXRSTEN APPARATUS AND METHODS FOR REPLACING THE KNIFE UNITS OF A WOODCUTTING MACHINE 4 Sheets-Sheet March 21, 1967 P. A. KIRSTEN 3,399,755

APPARATUS AND METHODS FOR REPLACING THE KNIFE UNITS OF A WOODCUTTING MACHINE Filed June 11, 1965 4 Sheets-Sheet 5 March 21, 1967 P. A. KIRSTEN 3,309,765

APPARATUS AND METHODS FOR REPLACING THE KNIFE UNITS OF A WOODCUTTING MACHINE 4 Sheets-Sheet 4 Filed June 11, 1965 United States l atent Office 3,309,765 APPARATUS AND RETHGDS FOR REPLAC- INC- THE KNIFE UNETS OF A WOODCUT- TING MACHINE Paul Arthur Kirsten, Ernst-Moritz-Arndt-Strasse 6, Beuel, near Bonn, Germany Filed June 11, 1965, Ser. No. 463,366 Claims priority, application, Germany, June 13, 1964, K 53,219 12 Claims. (Cl. 29401) This invention relates to methods and apparatus for replacing the knife units in a woodcutting machine.

It is known to reduce the time required for changing the knife units in woodcutting machines by adjusting the knife units outside the machine on two holders or inserts or the like and by fixing these units comprising knives and tool holders without screws in the tool carrier. With cylindrical tool carriers this is effected, for example, by the centrifugal force of chucking wedges, and with cylindrical carriers this is effected by means of springs wherein the tool holders are freed by hydraulic means. In order to reduce and facilitate manual work there are known compressed air operated extracting and inserting devices for the tool holders with knives for cylindrical tool carriers, and magnetic lifting devices for inserts with knives for disc-shaped tool carriers. Whilst one set of these units is mounted on the running machine, at least one set is fitted with ground knives and kept in readiness for knife replacement.

These known quick action devices for the knife change have been successful in reducing the undesirable and unproductive standstill times of machines. However, it is a drawback that the heavy knife holders or inserts of large machines with long knives require a great physical effort which is also rather time consuming. However, even in the case of comparatively light units of knife holders and knives a further reduction of the unproductive machine time for the knife change is desirable in order to improve the economy of the cutting machines.

An object of the invention is to provide improved apparatus and methods for replacement of knife units which avoids the above deficiencies.

According to the invention, this object is fulfilled by providing a frame with receiving stations for the knifeandknife holder units and moving it into such a position relative to the tool carrier that the units may be moved from the tool carrier into the receiving stations of the frame and vice-versa by mechanical, electromagnetic, pneumatic or hydraulic means. For tool carriers with a large number of knives or with very heavy units, the frame may be equipped with fewer receiving stations than the tool carrier so that two or more frames are required for a knife change.

The invention will be further described by way of example with reference to the accompanying drawing, showing two embodiments thereof, and in which:

FIG. 1 is a side elevation of a cutting machine with disk-shaped tool carrier;

FIG. 2 is a cross-section along the line A-B in FIG. 1;

FIG. 3 is an elevational view of a cutting machine with cylindrical tool carrier, in the upper half with annular frame and in the lower half 'without the same;

FIG. 4 is a side elevation of FIG. 3 wherein the upper half of the knife ring and annular frame is shown in cross-section along the line CD in FIG. 3.

FIGS. 1 and 2 show an embodiment of the invention in the form of a disk-shaped tol carrier 1 rotating about a shaft 2. The too carrier is fitted with inserts 31-36 in which are mounted marking knives 4 and cutting knives 5. The wood 7 to be cut is mounted on a support 6 and pressed by a feeding mechanism against the end face of the tool carrier 1 over which the markers 4 and the cutting knives 5 project in accordance with the required thickness of the chips.

Ereferably, the inserts 31-36 are fitted without screws in the tool carrier 1 in that they engage positively along the periphery of the tool carrier while a resilient looking bar presses each insert from the centre of the tool carrier towards the periphery thereof (lower half of FIG. 2). The actual chucking of the inserts is achieved by the centrifugal force of the inserts, locking bars and of the parts connected therewith.

FIGS. 1 and 2 show a cutting machine at standstill in which the markers 4 and the cutting knives 5 in the inserts 3136 have become blunt and must be replaced.

A frame 8 according to the invention contains an exchange set of inserts 41 to 46 with reground markers 4 and cutting knives 5 adjusted cotrectly relative to the end face of the inserts and ready to be fitted into the machine. As may be seen from the drawing, the frame 8 is fitted into a fixed guide 9 which is conveniently rigidly or detachably connected with the main frame 1% of the machine. As shown in FIG. 1, the frame 8 has on its left side (in the centre of FIG. 1) an empty receiving station for the insert 31.

Ratchets and locking bars ensure that during the fitting of the frame 8 into the guide 9 the empty receiving station is positioned exactly so that it faces the insert 31 of the tool carrier 1. The corresponding position of the tool carrier 1 is fixed by a locking bar 11 which engages into a recess 12 of the tool carrier. The locking bar 11 may be actuated by a cylinder 13 or by an electromagnet. The frame 8 has windows 14 through which a plate magnet 15 can be moved (FIGS. 1 and 2) by means of a hydraulic or pneumatic actuating cylinder 16.

Guide rods 17 of the plate magnet 15 are mounted in the guide 9 and/ or directly on the main frame 10 so that with locking bar 11 engaged, the plate magnet faces exactly one of the inserts 31 to 36 of the tool carrier 1.

The frame 8 with the inserts 41 to 46 holding the ground knives may be fitted into the guide 9 during the operation of the machine so that the empty receiving station of the frame is aligned with the plate magnet 15 which is now in its right hand terminal position in which it abuts against supports 18 of the guide rods :17 located on the frame or on the main frame of the machine (FIG. 2, top).

The automatic knife change is effected after stopping the machine in the following manner:

The tool carrier 1 is rotated by a main motor 19 or an auxiliary motor and this rotation is stopped by the locking bar 11 entering one of the notches 112. Thereafter, a hydraulic or pneumatic impulse is given to the cylinder 16 of the plate magnet 15 by mechanical and/or electrical and/or hydraulic and/or pneumatic controls and connections whereby this plate magnet is pushed through the window of the empty receiving station of the frame 9 to the insert 31. Instead of the employment of main motor 1? or an auxiliary motor, the indexing movement may also be effected by an operating cylinder by means of a cam plate (not shown) as known in the art.

Through mechanical and/ or electrical and/ or hydraulic and/or pneumatic controls and connections (not shown and known in the art) an impulse is applied to a hydraulic or pneumatic cylinder unit 20 whose piston rod 21 unlocks the insert 31 and moves it into the exchange position.

By energizing the magnets and gripping the insert 31 and by means of an impulse passing through the controls and connections whereby the plate magnet 15 with the adhering insert is pushed back, this insert is transported into the empty receiving station of the frame 8. This position of the plate magnet 15 with insert 31 is shown in FIG. 2. This position of the insert in the frame is se- Patented Mar. 21, 1967- cured, by means not shown and known in the art, by spring loaded locks or the like. The guide 9 or the housing for the tool carrier 1 may be equipped with nozz-les whereby after the removal of the insert from the tool carrier the free receiving station is blown out with compressed air.

Simultaneously with the movement of the insert into the empty receiving station the magnets are de-energized through the controls and connections and the plate magnet is moved into abutment against the supports 18; simultaneously an impulse to the motor 22 or a corresponding known hydraulic or pneumatic or mechanical Cylinder unit with a switching rod causes a longitudinal displacement of the frame 8 by one station t (FIG. 1) in its guide moving the insert 41 into alignment with the plate magnet. Then an impulse is applied to the cylinder 16 of the magnet whereby the same is moved through the Window 14 of the frame 8 into abutment with the insert 41.

By energizing the magnets, gripping the insert 41 and .transporting it into the tool carrier 1, and by de-energiz ing the magnets, an impulse is applied to the cylinder 20 whereby its piston rod 21 is retracted and the insert 41 is locked by a spring 23.

An impulse applied through the controls and connections to the cylinder 13 causes the locking bar to be retracted and a further impulse applied to the motor 19 effects the rotation of the tool carrier 1 through one indexing position. 7

Then the tool carrier 1 is stopped by the locking bar 11 penetrating into the next notch 12 causing a new impulse to be applied to the cylinder 20 whereby the insert 32 in unlocked from the tool carrier.

Thus, the switching on of the magnets, the gripping and transport of the inserts 32 into the frame 8 and all other actions continue automatically until all knife inserts have been replaced. The machine can now be put into operation. The frame 8 with the inserts 31 to 36 is taken off the guide 9 the knives are reground, adjusted in the inserts and tightened Then the inserts are replaced in the frame and the frame may be held in readiness for the next knife change or may be immediately fitted into the guide.

FIGS. 3 and 4 show another embodiment of the invention in which a cutting machine has a cylindrical tool carrier 101 rotating about a shaft 102. This tool carrier has the form of a dished disk. The knives 103 are located on the inner cylindrical surface of the dish and the word to be cut and having a length of about 3 cm. is thrown against the inner surface of the dish by a rotating cross 104 having a sense of rotation opposite to that of the tool carrier 101.

The knives 103 are connected by screws with knife holders 105 as known in the art. The units 131 to 142 consisting of knives and knife holders are lifted off the tool carrier for grinding and setting the knives. An exchange set of units 151 to 162 is available in order to reduce to a minimum the inoperative machine time. In order to carry out the actual knife change as quickly as possible it has hitherto been the practice of using chucking wedges 106 suspended by heads 107 in the tool carrier 101, slightly movable in a substantially radial direction and slightly pressed by springs 108 towards the interior of the tool carrier when the machine is at standstill. In this way, the units 131 to 142 which are unblocked may be extracted vaxially by hand and units 151 to 162 with ground knives may be inserted.

It is also known to dismantle for the knife change the knife carrier ring from the tool carrier 101 and to replace it by another ring with ground knives. This required prior dismantling of the cross 104 which was complicated :and time-wasting, especially with large machines and usually led to eccentricities of the bodies revolving at high speeds.

According to the invention, this know construction may be modified and improved by providing an annular frame 109 with receiving stations 110 containing a set of units 152 to 162 with ground knives 103, the number of these units being preferably smaller byone (e.g. 151) and to place this frame 109 concentrically and rotatively in front of the tool carrier 101 so that the units 131 to 142 containing the blunt knives may be exchanged for units 152 to 162 containing sharp knives as in the first embodiment. The unit 151 is fitted after the removal of the annular frame 109 into the empty receiving station 142 of the tool carrier 101. It would theoretically be possible to arrange an empty receiving station, say between the stations 162 and 151 of the annular frame, that is to say, to arrange one station more in the frame than in the tool carrier. However, since these machines usually have a large number of knives in narrow spaced arrangement it is preferable to fit one unit manually.

A simple construction results by extending the shaft 111 of the throw cross 104 by a section 112 on which may be fitted the annular frame 109 consisting of flanges, spokes and hub.

The automatic knife change is effected automatically by means of electrical and/or pneumatic and/or hydraulic controls and connections, not shown and known in the art, in the following manner.

The machine is stopped and the door-shaped cover (not shown) which closes the machine housing 113 during the operation is opened.

The annular frame 109 holding the units 152 to 162 with ground knives is fitted to a stub 112 of the throw cross shaft 111 and a cylinder 114 whose piston rod carries on its free end a magnet 115 is pivoted downwards. The joint 116 on the machine is blocked.

The tool carrier 111 is rotated by its motor I through a belt pulley 117, an operating cylinder with cam plate or the like and the rotation is stopped by a locking bar 118 entering into a notch 119. The annular frame 109 is rotated by hand until an empty receiving station, e.g. 151 is aligned with the magnet 115. A locking bar 120 en gages into a notch 121 and the annular frame is blocked by hand on the stub 112. An impulse is applied to the cylinder 114 causing the magnet 115 to be displaced to wards the unit 131.

Energization of the magnet causes this unit 131 to be gripped and it will now be guided in the annular frame 109 into abutment with its outer flange.

An impulse is now applied to the cylinder 122 whereby the locking bar 120 is extracted from the notch 121 and simultaneously an impulse is applied to a motor II (working cylinder with cam plate) which rotates through a pulley 123 the shaft 111 and with it also the annular frame 109. This rotational movement is again stopped when the locking bar 120 enters into the next notch 121. Then the unit 152 is transferred from the annular frame 109 into the tool carrier 101.

An impulse is applied to the cylinder 124 causing the locking bar 118 to be removed from its notch 119.

Then an impulse is applied to the motor I whereby the tool carrier 101 is rotated until the locking bar 118 engages into the next notch 119. The magnet 115 grips the insert 132 and transfers it into the annular frame 109.

An impulse is applied to the cylinder 122 which withdraws the locking bar 120 from its notch and this process is continued until the units 131 to 142 have been transferred to the annular frame 109 and the units 152 to 162 into the tool carrier 101.

Then the cylinder 114 is pivoted upwardly about the joint 116 the blocking between the shaft 112 and the annular frame 109 is slackened and the frame is removed.

Finally, the unit 151 is inserted by hand into the free receiving station of the tool carrier 101 and the housing 113 is closed.

During the operation of the machine the inserts 131 to 142 are lifted off the annular frame, the knives 103 are ground adjusted in the knife holders 105 and tightened., Then the inserts 132 to 142 are fitted into the annular frame and the same is prepared for the next knife change.

Naturally, several cylinders may be provided instead of one whereby the stepping frequency for the tool carrier 101, the annular frame 109 etc. can be reduced.

Having thus fully disclosed the invention, what is claimed as new and is desired to be secured by Letters Patent is:

1. A device for automatically replacing the knife units in a rotatable carrier of a woodcutting machine, said device comprising a frame having a plurality of receiving stations one of which is empty while the remainder are adapted for containing replacement knife units, means for moving the frame and carrier relative to one another between index positions in which the receiving stations in the frame are brought into successive registration with the knife units in the carrier, and means for both removing individual knife units from the carrier one at a time and placing the same into the frame and for removing individual replacement knife units from the frame and placing them into the carrier.

2. A device as claimed in claim 1, wherein the frame having the receiving stations comprises an annular frame arranged concentrically and rotatably in front of the tool carrier.

3. A device as claimed in claim 1 wherein said said frame is supported for slidable displacement at a location adjacent the carrier such that said stations can be brought into registry with the knife units by rotation of the carrier and displacement of the frame.

4. A device as claimed in claim 1 wherein said frame is mounted for rotation adjacent the carrier, said stations being in an annular arrangement corresponding to the arrangement of the knife units on the carrier such that said stations can be brought into registry with the knife units by relative rotation of the carrier and frame.

5. A device as claimed in claim 1 wherein the frame has one receiving station more than the carrier has knife units.

6. A device as claimed in claim 1 wherein said means for removing the knife units and the replacement knife units comprises a plate magnet having extended and retracted positions, said plate magnet being mounted adjacent said frame and carrier for passing through the re ceiving stations of the frame.

7. A device as claimed in claim 1 wherein said carrier includes means displaceably supporting the knife units therein.

8. A device as claimed in claim 1 wherein said carrier includes means resiliently and detachably supporting the knife units therein, comprising a spring-loaded displaceable locking mechanism including an actuating locking bar, said carrier having a groove in the periphery thereof for accommodating the knife units, the latter units being locked in the carrier and being unlocked upon displacement of the locking bar.

9. In a woodcutting machine having a rotatable carrier with replaceable knife units: means for replacing the knife units with replacement units, said means comprising a frame having a plurality of receiving stations adapted for containing replacement knife units, means for moving the frame and carrier relative to one another between index positions in which the receiving stations are brought into successive registration wtih the knife units in the carrier, and means for removing successive knife units one at a time from the carrier and transferring them to the frame and alternately replacing the knife units with replacement units from the frame.

16. In a machine as claimed in claim 9 wherein the last said means comprises a displaceable plate magnet having extended and retracted positions, said frame and carrier being disposed adjacent to one another, the plate magnet being supported adjacent the frame for passing through an empty receiving station and engaging a knife unit to be replaced for moving such knife unit into the empty receiving station for being supported therein, said plate magnet being movable from the retracted to the extended position for engaging a replacement knife unit in the frame and transferring such unit to the carrier for being supported therein in the vacant space left by a previously removed knife unit.

11. A method of replacing removable knife units on a rotatable carrier of a woodcutting machine, said method comprising detachably connecting replacement knife units in receiving stations in a frame, moving the frame and carrier relative to one another between index positions to successively align the receiving stations one at a time with the units in the carrier, and successively moving one knife unit from the carrier to the frame and then replacing the knife unit with a replacement unit in the carrier.

12. A method as claimed in claim 11 wherein the first receiving station is empty, and is initially placed in registry with a knife unit which is to be replaced after which the latter unit is removed from the carrier and placed in the empty receiving station, the carrier and frame then being rotated to successive index positions in which the replacement knife units are placed in the carrier and the knife units in the carrier are placed in the frame in alternation.

References Cited by the Examiner UNITED STATES PATENTS 2/1951 Seybold 2920O 5/1965 West 29-401 

11. A METHOD OF REPLACING REMOVABLE KNIFE UNITS ON A ROTATABLE CARRIER OF A WOODCUTTING MACHINE, SAID METHOD COMPRISING DETACHABLY CONNECTING REPLACEMENT KNIFE UNITS IN RECEIVING STATIONS IN A FRAME, MOVING THE FRAME AND CARRIER RELATIVE TO ONE ANOTHER BETWEEN INDEX POSITIONS TO SUCCESSIVELY ALIGN THE RECEIVING STATIONS ONE AT A TIME WITH 